Drill pointing method and machine



Dec. 11, 1962 J. c. WINSLOW DRILL POINTING METHOD AND MACHINE 3Sheets-Sheet 1 Filed June 6, 1960 IN V EN TOR. J mss C fl4/vszon Dec.11, 1962 J. c. WINSLOW 3,067,548

INVENTOR. 44155 6. IV/Mszau Dec. 11, 1962 J.-C. WINSLOW DRILL POINTINGMETHOD AND MACHINE 5 Sheets-Sheet 3 Filed June 6, 1960 W mm y W m a e 5;m M 4 2% w United States Patent 3,067,548 DRILL POINTING METHOD ANDMACHINE James C. Winslow, Sierra Madre, Calif, assignor to WinslowProduct Engineering Corporation, Arcadia, Calif., a corporation ofCalifornia Filed June 6, 1960, Ser. No. 33,972 Claims. (6]. 5194) Thisinvention deals generally with the art of pointing drills andparticularly with improvements in the drill pointing method and machinedisclosed in copending application Serial No. 815,509 filed May 25,1959, for Drill Pointer.

Briefly, the drill pointing machine of the copending applicationcomprises a holder for a drill to be pointed, a rotary grinding wheelhaving a coaxial grinding surface terminating in a coaxial grindingedge, and means for synchronously rotating the drill and relativelymoving the latter and grinding wheel in such a way that the relativemovement of the drill tip is over the grinding surface and across thegrinding edge. These movements are timed so that a relief or hollow isground in the trailing edge of each lip of the drill to provide thelatter with a relatively sharp center point.

The present invention provides a grinding wheel for use on the priordrill pointing machine to adapt the latter to grinding conventionaldrill points. In such a conventional point, the lips of the drill aretapered toward their trailing edge to provide clearance but are nothollow ground.

A general object of this invention is, therefore, to provide an improvedmethod of and machine for grinding conventional points on drills.

Another object of the invention is to provide an improved grinding wheelfor use in grinding conventional drill points.

Other objects, advantages and features of the invention will becomereadily apparent as the description .proceeds.

Briefly, these objects are achieved by providing the prior drillpointing machine with a grinding Wheel having a beveled peripheralgrinding surface tangentially merging into a convex peripheral grindingsurface. This grinding Wheel and the drill to be pointed are relativelymoved and the drill is rotated in such a way that the relative movementof the rotating drill tip is over the beveled grinding surface towardand finally across the circular line of tangency of the two grindingsurfaces.

These movements are timed so that a relief angle is ground on each lipof the drill without undercutting or hollow grinding the trailing edgeportions of the lips. A conventional point is thus formed on the drill.

The invention may be better understood from the following detaileddescription thereof, taken in connection with the annexed drawings,wherein:

FIG. 1 illustrates the present grinding wheel installed on the priordrill pointing machine;

FIG. 2 is a View on enlarged scale looking in the direction of thearrows on line 2-2 in FIG. 1;

FIG. 3 is an enlarged view illustrating the position of initial contactof the drill tip and grinding wheel during each grinding pass of thedrill;

FIG. 4 is an end view of the drill tip in FIG. 3;

FIG. 5 is a view similar to FIG. 3 illustrating the drill tip in anintermediate position;

FIG. 6 is an end view of the drill tip in FIG. 5;

FIG. 7 is a view similar to FIG. 3 illustrating the final position ofcontact of the drill tip and grinding Wheel during each grinding pass ofthe drill;

FIG. 8 is an end view of the drill tip in FIG. 7;

ice

FIG. 9 is a semi-diagrammatic illustration of certain mechanism of themachine; and

FIG. 10 is a section, on reduced scale, taken along line 1;0-10 in FIG.9.

In these drawings, the prior drill pointing machine is denoted by thenumeral 10. As described more fully in the prior application Serial No.815,509, this machine comprises a drill holder '12 which is oscillatedand reciprooated on a vertical axis 13 by mechanism (FIGS.

9 and 10), soon to be described, within the frame or base 14 of themachine.

The grinding wheel 16 of this invention is mounted on the vertical,rotatably driven spindle 18 of the machine 10. As shown best in FIGURE3, this grinding wheel is formed with a beveled, peripheral grindingsurlface 20, the intersection of which with a plane containing the axisof the grinding wheel is approximately a straight line, and a convex,peripheral grinding surface 22 which merges tangentially with thebeveled grinding surface. The coaxial line or zone Z of tangency ofthese two grinding surfaces is located in a plane 24 normal to the axisof the grinding wheel.

The convex grinding surface 22 has been shown as being circularly curvedin a radial plane of the grinding wheel and to have a radius R. It willbecome evident as the description proceeds, however, that the surface 22may have other than a circular curvature.

A drill 26 to be pointed is inserted through a fixed drill bushing 28carried by the drill holder 12 to a position wherein the tip of thedrill is located a slight distance beyond the forward end of thebushing, as may be observed best in FIGS. 3, 5 and 7. During operationof the machine, the drill 26 is rotated in the fixed bushing 28 insynchronism with oscillation and reciprocation of the drill holder 12 tomove the drill tip past the grinding wheel 16 in the manner illustratedin FIGS. 3-8. The above movements of the drill holder 12 and the drill26 are produced by the mechanism 100 illustrated in FIGS. 9 and 10, towhich reference is now made. Since the present grinding machine 10,except for the grinding wheel 16, and including the drill holder 12 andthe mechanism 100, is identical to that of copending application SerialNo. 815,509, drill holder 12 and mechanism 100 have been illustrated insemi-diagrammatic fashion in FIGS. 9 and 10 and will be only brieflydescribed herein. If a more detailed description of these parts isdesired, therefore, reference should be had to application Serial No.815,509.

In FIGS. 9 and 10, drill holder 12 will be observed to comprise avertical, tubular post 102 which is supported on the base 14 forrotation and axial movement on the axis 13. Mounted on the upper end ofpost 102 is a hollow, generally semicyclindrical head structure 104having a forward wall in which the drill bushing 28 is fixedly mounted,as shown, Rotatably supported in the head 104, behind the bushing 28, isa worm gear 106 which turns on the axis of the bushing. This gearcarries diametrically opposed, radially movable chuck jaws 108 backed upby plungers 110 and balls 112. Head 104 has a rear, annular hydrauliccylinder 114 coaxial with the gear 106. In this cylinder is an annularpiston 116. When hydraulic fluid under pressure is admitted to thecylinder 114, at the rear of the piston 116, through an inlet 118,piston 116 is moved forwardly.

Rotatably supported on the forward end of the piston 116 is a coaxial,annular cam 120 having a conical inner cam surface 122 bearing againstthe balls 112. When piston 116 is moved forwardly by fiuid pressure incylinder 114, chuck jaws 108 are cammed inwardly to grip the shank ofthe drill 26 positioned in the drill bushing 3 28. Rotation of gear 106,then, rotates the drill in the bushing.

Worm gear meshes With a worm 14 rotatably supported in the head 104 forturning on the axis 13. Extending axially through the post 102 is arotary drive shaft 126 which is drivably connected at its upper end tothe worm 124. The lower end of the shaft 126 is drivably coupled to amotor 128, as diagrammatically indicated in FIG. 9, for rotation of theshaft 126 by the motor. Accordingly, when a drill 26 is positioned inthe bushing 28 and the chuck jaws 108 are set, motor 128 drives thedrill in rotation in the bushing through the shaft 126 and gears 106,124.

Indicated at 130 is a bell crank which is pivoted on the machine base 14and includes an arm 132 engaging a roller 134 on the lower end of thepost 102. The other arm of the bell crank 130 carries a cam followerroller 136 which rides on a cam disc 138. Cam disc 138 is shaped to rockthe bell crank lever 130 in a direction to urge the bell crank arm 132against the post roller 1'34 and thereby rotate the post 102, and,hence, the entire drill holder '12, on the axis 13. A spring-loadedroller 140, mounted on a part 142 of the machine base 14 and engaging alongitudinal surface 144 on the post 102, urges the latter, and, hence,the entire drill holder 12, in the opposite direction on axis 13. Duringcontinuous rotation of cam 138, then, the drill holder 12 is oscillatedon the axis 13.

Indicated at 146 is a second cam disc which engages a cam followerroller 148 carried on and located intermediate the ends of an arm 150.One end of arm 150 is pivotally attached to a vertically positionable ormovable rod 152 which is vertically positionable or movable by a means154 labeled elevating means for reasons to be seen shortly. The otherend of arm 150 comprises a fork which straddles the shaft 126 andcarries a pair of rollers 156 (only one shown) on which, the lower endface of post 102 rests. Post 102 and, therefore, the entire drill holder12 are thus rotatably supported on the forked end of the arm 150. Whenrod 152 is stationarily located in its position of FIG. 9, rotation ofcam 146 rocks the arm 150 about its pivotal connection to the rod andthereby causes reciprocation of the drill holder 12 along the axis 13,the drill holder being elevated by the cam and returned downwardly underits own weight. Cams 138 and 146 are drivably coupled to the motor 128,as diagrammatically indicated in FIG. 9, for rotation of the cams inunison by the motor.

From the preceding description, it is evident that during operation ofmotor 128, shaft 126 and cams 138, 146 are driven in rotation insynchronism so that the drill holder 12 is synchronously oscillated andreciprocated on the axis 13 and the drill 26 is rotated in the drillbushing 28 in synchronism with oscillation and reciprocation of thedrill holder.

Elevating means 154 is operable to shift the rod 152 downwardly from itsposition of FIG. 9 while the cams 138, 146 are stationary. When thisoccurs, arm 150 is rocked on the cam 146, about its cam follower roller148 as a center, and elevates the drill holder 12. Elevating means 154is arranged to elevate the drill holder 12 in this way to the loadingposition of the drill holder, shown in solid lines in FIG. 1, whereinthe drill bushing 28 in the drill holder is axially aligned With a fixeddrill locator 158 on the machine.

Indicated at 160 is a control system for energizing the motor 128,controlling the drill holder elevating means 154, and the admission ofhydraulic fluid to the drill holder chuck cylinder 114. Control system160 is identical to that described in the aforementioned copendingapplication Serial No. 815,509 and, therefore, has been onlydiagrammatically illustrated in FIG. 9. Control system 160 is arrangedto effect the following sequence of operations of the machine:

The drill holder elevating means 154 is initially operated to elevatethe drill holder 12 to its solid line, loading position of FIG. 1. Adrill 26 to be pointed is now inserted through the bushing 28, from therear, until the tip of the drill engages the drill locator. The drilllocator locates the drill in a predetermined angular position and apredetermined axial position in the drill holder. The tip of the drillthen extends slightly beyond the forward end of the drill bushing 28, asshown in FIG. 3. Hydrau lic fluid under pressure is then admitted to thechuck cylinder 114 of the drill holder to cause the chuck jaws 108 togrip the drill shank.

Drill holder elevating means 154 are next operated to lower the drillholder to its initial grinding position of FIGS. 3 and 4 and the motor128 is energized. In the initial grinding position of the drill holder,initial contact is established between the drill tip and the grindingwheel '16. In this position of initial contact, one lip 30 of the drillengages the beveled grinding surface 20 of the grinding wheel along theleading edge 32 of the lip and this edge is disposed approximately in aplane containing the axis of the grinding wheel, as shown. The leadingedge of the lip is thereby ground to form a cutting edge.

Motor 128, now energized, drives the cams 138, 146 and the drill 26 insynchronized rotation. Rotation of these parts is so synchronized andthe cams 138, 146 are so shaped as to effect the following grindingcycle:

From the position of initial contact of FIGS. 3 and 4, the drill holderis swung toward the grinding wheel and is simultaneously axially movedin the upward direction while the drill is synchronously rotated in theholder to bring the trailing surface area of the lip behind its leadingedge 32 into contact with the grinding surface. This rotation of thetrailing surface area of the lip into contact with the grinding surfacesimultaneously with axial advancement of the drill tip toward thegrinding surface and transverse movement of the tip toward the convexgrinding surface 22 grinds a relief angle on the lip.

These three movements are timed so that the drill tip passes through theposition of FIG. 5, in which both the drill axis and the chisel edge 36of the drill are located in the plane of tangency 24 of the two grindingsurfaces 20 and 22. In this position, the chisel edge is ground.

During continued axial, transverse and rotational movement of the drillfrom the position of FIG. 5, the tip of the drill moves across thecoaxial zone Z of tangency of the grinding surfaces 20 and 22 on thegrinding wheel onto the convex grinding surface 22 and the trailing endof the lip is rotated into contact with beveled grinding surface 20 tocomplete grinding of the relief angle on the lip.

It can be readily observed that in the grinding position of FIG. 5, thefinal trailing portion of lip 30 has not yet been ground so that thedrill tip must undergo further axial, transverse and rotational movementpast the grinding wheel to complete grinding of the relief angle on thelip. It will also be obvious that in order to avoid grinding of thechisel edge 36 away to a conical point during this continued movement ofthe drill tip beyond the position of FIG. 5, the center of the tip mustmove out of contact with the grinding wheel.

In the drill pointing machine of the copending application Serial No.815,509, the beveled grinding surface intersects the upper face of thegrinding wheel on a sharp circular grinding edge. The chisel edge of thedrill is ground just below this grinding edge and then immediately movesacross the latter edge out of contact with the Wheel. During thefollowing movement of the drill lip across the grinding edge, the lattergrinds a relief in the lip, as mentioned earlier.

In the present grinding machine, during continued movement of the drillbeyond the position of FIG. 5 to the final grinding position of FIG. 7,the trailing edge portion of the lip 30 is rotated past the grindingwheel to complete grinding of the lip relief angle The transversemovement of the drill between these positions moves the chisel edge 36out of engagement with the beveled grinding surface 2!), across thecoaxial zone Z f n en y f h grind ng su ac s n t convex grinding surface22 so that the final grinding of the lip in the tapered area 30'immediately adjacent to the chisel edge 36 is done by the convexgrinding surface. The chisel edge 36 is ground slightly by the lattergrinding edge and is thereby made slightly arcuate, as shown.

The drill holder 12 is now rotated away from the grinding wheel, todisengage the drill tip from the grinding wheel, and is lowered toreturn the holder to its initial grinding position of FIG. 3. Duringthis return of the drill holder to its initial grinding position,continued rotation of the drill 26 in the holder brings the leading edgeof the other lip of the drill into the correction position for initialcontact with the beveled grinding surface 20 of the grinding wheel,i.e., the position of FIG. 3. The above grinding cycle is then repeatedon the latter lip of the drill, after which the drill holder is againreturned to its initial grinding position of FIG. 3 and the first lip ofthe drill is reground, and so on. In the finished ground drill, then,the tip is formed with a conventional point in which both lips have arelief angle. The final chisel edge 6 is generally 8 shaped, as shown.

It will be obvious from FIG. 7 that if the beveled grinding surface 20extended to the top face of the grinding wheel, the chisel edge 36 wouldbe ground away to the axis of the drill in the final grinding positionof FIG. 7 and the other half of the chisel edge would be similarlyground away during grinding of the other lip.

If the drill tip moved across a circular grinding edge on the grindingwheel, on the other hand, as in the prior drill pointing machine, thelips of the drill Would be undercut, as explained in the priorapplication.

By providing the grinding wheel with the convex grinding surface 22, aconventional point, having lips which are not undercut, can be ground onthe drill without completely grinding away the chisel edge.

Clearly, therefore, the invention herein described and illustrated isfully capable of attaining the objects preliminarily set forth.

What is claimed is:

1. In a drill pointing machine, the combination of a frame, a rotarygrinding wheel on the frame having a first coaxial grinding surface, theintersection of which with a plane containing the axis of the wheel isapproximately a straight line, and a second coaxial, convex grindingsurface which merges approximately tangentially with said first grindingsurface along a coaxial zone of tangency, a drill holder on the frame,and means for effecting initial relative movement between said holderand the grinding wheel to bring the tip of a drill in the holder andsaid first grin-ding surface into initial contact with the drill axisinclined at a predetermined angle to the first grinding surface andsubsequent relative movement of the drill and grinding wheel past oneanother in such manner that the relative movement of the drill withrespect to the wheel is a compound movement involving relative,approximately axial movement of the drill toward said first grindingsurface and simultaneous relative lateral movement of the drill towardsaid second grinding surface and finally across said coaxial zone oftangency of said grinding surfaces, and means for rotating the drill insynchronism with said relative movement between the drill and grindingwheel.

2. In a drill pointing machine, the combination of a frame, a rotarygrinding wheel on the frame having a first beveled, peripheral grindingsurface and a second peripheral, convex grinding surface which mergesapproximately tangentially with said first grinding surface along acoaxial zone of tangency, a drill holder on the frame, and means foreffecting initial relative movement between said holder and the grindingwheel to bring the tip of a drill in the holder and said first grindingsurface into initial contact with the drill axis inclined at apredetermined angle to the first grinding surface and subsequentrelative movement of the drill and grinding wheel past one another insuch manner that the relative movement of the drill with respect to thewheel is a compound movement involving relative, approximately axialmovement of the drill toward said first grinding surface andsimultaneous relative lateral movement of the drill toward said secondgrinding surface and finally across said coaxial zone of tangency ofsaid grinding surfaces, and means for rotating the drill in synchronismwith said relative movement between the drill and grinding wheel.

3. In a drill pointing machine, the combination of a frame, a rotarygrinding wheel on the frame having a first coaxial grinding surface, theintersection of which with a plane containing the axis of the wheel isapproximately a straight line, and a second coaxial, convex grindingsurface, the intersection of which with said plane is a generallycircularly curved line and which merges approximately tangentially withsaid first grinding surface along a coaxial zone of tangency, a drillholder on the frame, and means for effecting initial relative movementbetween said holder and the grinding wheel to bring the tip of a drillin the holder and said first grinding surface into initial contact withthe drill axis inclined at a predetermined angle to the first grindingsurface and subsequent relative movement of the drill and grinding wheelpast one another in such manner that the relative movement of the drillwith respect to the wheel is a compound movement involving relative,approximately axial movement of the drill toward said first grindingsurface and simultaneous relative lateral movement of the drill towardsaid second grinding surface and finally across said coaxial zone oftangency of said grinding surfaces, and means for rotating the drill insynchronism with said relative movement between the drill and grindingwheel.

4. In a drill pointing machine, the combination of a frame, a rotarygrinding wheel on the frame having a first beveled, peripheral grindingsurface and a second peripheral, generally circularly curved, convexgrinding surface which merges approximately tangentially with said firstgrinding surface along a coaxial zone of tangency, a drill holder on theframe, and means for effecting initial relative movement between saidholder and the grinding wheel to bring the tip of a drill in the holderand said first grinding surface into initial contact with the drill axisinclined at a predetermined angle to the first grinding surface andsubsequent relative movement of the drill and grinding wheel past oneanother in such manner that the relative movement of the drill withrespect to the wheel is a compound movement involving relative,approximately axial movement of the drill toward said first grindingsurface and simultaneous relative lateral movement of the drill towardsaid second grinding surface and finally across said coaxial zone oftangency of said grinding surfaces, and means for rotating the drill insynchronism with said relative movement between the drill and grindingwheel.

5. The method of pointing a drill with a rotary grinding wheel having afirst coaxial grinding surface, the intersection of which with a planecontaining the axis of the wheel is approximately a straight line, and asecond convex, coaxial grinding surface which merges approximatelytangentially with said first grinding surface along a coaxial zone oftangency, said method comprising the steps of relatively moving thedrill and grinding wheel toward one another to bring the drill tip andfirst grinding surface into contact with the drill axis inclined at apredetermined angle to the first grinding surface and thereafterrelatively moving the drill and grinding wheel past one another in suchmanner that the relative movement of the drill with respect to the wheelis a compound movement involving relative, approximately axial 8movement of the drill toward said first grinding surface ReferencesCited in the file of this patent and simultaneous relative lateralmovement of the drill UNITED STATES PATENTS toward sa1d second grlndlngsurface and finally across said coaxial zone of tangeney of saidgrinding surfaces, 732,949 Koenig y 1903 and simultaneously rotating thedrill in synchronism with 5 1,379,853 Cogsdln y 1921 said relativemovement between the drill and grinding 2,015,727 Prey 1935 wheel. 1Siennsen et a1 Dec. 10, 1957

